Process for forming a flared end tubular metal part

ABSTRACT

A two-step cold forming process for forming a flared end tubular metal part in a press having a lower fixed support and a downwardly movable upper press ram, comprising the step of extruding the lower portion of a short tubular blank, whose diameter is approximately equal to the diameter of the flared end of the part, into approximate finished length and diameter by means of pressing downwardly an elongated, cylindrical punch, mounted upon the press ram, against and through the blank positioned in a flared diameter, vertically axised, die opening in a die mounted upon the press support, and thereafter, the step of expanding the upper portion of the blank to the exterior and internal diameters of the flared portion of the part in a second die opening in a press support mounted die, with a second ram mounted, flared diameter punch pressed downwardly through the extruded part.

United States Patent [1 1 Jesmore et al.

PROCESS FOR FORMING A FLARED END TUBULAR METAL PART Inventors: WilliamD. Jesmore, I-luntingdon;

Joseph A. Simon, Grosse Pointe Farms, both of Mich.

Assignee: U.S. Manufacturing Corporation,

Detroit, Mich.

Filed: Jan. 6, 1972 Appl. No.: 215,850

[111 3,739,620 June 19, 1973 Primary Examiner-Richard J. HerbstAssistant Examiner-Robert M. Rogers Attorney-Bernard J. Cantor [57]ABSTRACT A two-step cold forming process for forming a flared endtubular metal part in a press having a lower fixed support and adownwardly movable upper press ram, comprising the step of extruding thelower portion of a short tubular blank, whose diameter is approximatelyequal to the diameter of the flared end of the part, into approximatefinished length and diameter by means of pressing downwardly anelongated, cylindrical punch, mounted upon the press ram, against andthrough the blank positioned in a flared diameter, vertically axised,die opening in a die mounted upon the press support, and thereafter, thestep of expanding the upper portion of the blank to the exterior andinternal diameters of the flared portion of the part in a second dieopening in a press support mounted die, with a second ram mounted,flared diameter punch pressed downwardly through the extruded part.

3 Claims, 7 Drawing Figures PROCESS FOR FORMING A FLARED END TUBULARMETAL PART BACKGROUND OF INVENTION The invention herein relates to thecold forming of elongated, flared end tubular parts, such as a spindlehousing used for journalling the axle of a truck wheel. Parts of thistype, are generally cylindrically tubular in shape with one end of anenlarged or flared diameter and are usually made of steel.

In the past, such parts have been cold formed by an upwards forgingtechnique, wherein a blank is inserted into a die located upon the bedor table or support of a forging press and then a ram mounted spindle orpin is pressed into the part for cold flow of the metal upwardly aroundthe spindle. The enlarged flared portion has typically been forged atthe lower end of the part during the forging process. In this priorprocess, the part has been formed, step by step, through a series ofthree, four or five steps, into a finished forged part.

In this prior type process, the finished part is not dimensionallyaccurate and requires some considerable machining for accurate sizing,after the forging process. In addition, the formation of the part isrelatively expensive because of the number of press steps required,particularly since it is customary to heat treat or anneal between eachpress step and to re-lubricate the part and the press dies during thissort of process.

Hence, the invention herein relates to a simplified process for formingflared and tubular parts by a cold forging process which is so modifiedand improved as to reduce the number of steps in the press, therebyconsiderably reducing the cost of production, and in addition produce apart which is of considerably greater accuracy than that produced priorto the invention herein.

SUMMARY OF INVENTION The invention herein contemplates cold forming aflared and tubular part, such as a truck spindle housing or the like, bymeans of first forming a short, centrally bored blank of approximatelythe diameter of the flared end of the part. Thereafter, the blank isinserted into a die opening formed in a die fastened upon the fixedtable or support of a forging press, with the die opening preferablyvertically axised. Next, a punch presses down against the top of theblank to extrude its lower end around a punch extension spindle whichfunctions like a central mandrel, so that the part main body portion isextruded downwardly into the die opening into the approximate length andoutside diameter required, but with a uniform central bore.

Following the extrusion step, the part is placed into a second dieopening, similar to the first, and with a second punch, also having aspindle or pin extension arranged within the bore of the body of thepart. The punch expands the flared end of the part to desired OD. andID. Hence, the process essentially involves an extrusion step using adownwardly moving punch for extruding the body portion of the partdownwardly into the die opening, and thereafter, an expansion step,

using a similar punch and die opening for expanding the flared end ofthe part to correct size.

By heating the part before each step, to a temperature below thetransition temperature of the metal, as

for example, to a temperature of roughly 1,200F, the extrusion andexpansion steps may be accomplished with relatively low pressures,without changing the metallurgical structure. Thus, although the processis referred to herein as cold forming, it may better be referred to aswarm forming, that is, not at room tem- DESCRIPTION OF DRAWINGS FIG. 1is an elevational view of a flared end spindle housing.

FIG. 2 is a view similar to FIG. 1, but showing the part incross-section.

FIG. 3 is a cross-sectional, perspective view of a blank from which thepart is made.

FIG. 4 schematically shows the positioning of the blank within a dieopening.

FIG. 5 shows the extrusion step, and

FIG. 6 shows the expansion step.

FIG. 7 is an enlarged view of the upper end of the part, incross-section, showing in dotted lines the part after the extrusionstep, and in solid lines, the finished part.

DETAILED DESCRIPTION FIGS. 1 and 2 illustrate a flared end tubular metalpart 10, as for example, a steel spindle housing within which a truck.wheel axle may be journalled. The process herein is particularlyadaptable for the production of such type parts having an elongatedtubular body portion and a flared or enlarged end integral therewith.

The part 10 includes the elongated, cylindrically shaped body portion11, having a central bore 12, and a flared or enlarged diameter end 13with an enlarged internal or flared bore 14. For illustration purposes,the exterior of the part is further widened or enlarged at a mid portion15 between the flared end and the body.

In order to manufacture the part 10, a suitable blank 18 is formed.Preferably, the blank is formed of seamless tubing of an appropriatesteel and is formed with a central bore 19. The blank may be formed bycutting lengths of seamless tubing into the blanks lengths and machiningwhere necessary to appropriate size.

The blank is processed within a die 20, schematically shown, mountedupon the fixed table or fixed support 21 of a forging press. The pressand the method of securing the die are conventional and thus shown onlyschematically. The die has a vertically axised die opening 22 having anupper flared end 23, a narrowed mid portion 24 forming a shoulder 25with the upper flare end portion, and a straight, cylindrically shapedlower end 26. Thus, the die opening is formed in several steps.

The blank is dropped into the flared upper end 23 of the die opening sothat it is coaxial therewith and fits fairly closely within the dieopening.

Arranged above the die opening, is a vertically axised punch 27,appropriately mounted upon the movable ram 28 of the press for downwardmovement under press pressure. The punch includes an enlarged bodyportion 29 and a central, downwardly extending narrower spindle or pinor punch shaft 30 of a diameter to fit within the bore 19 of the blank18. A pushing shoulder 31 is formed on the lower end of the body portion29 of the punch.

Referring to FIG. 5, after the blank has been positioned within the dieopening (FIG. 4), the ram of the press is actuated to push the punchdownwardly so that its pushing shoulder 31 engages and pushes downwardlyupon the upper edge of the blank. The punch spindle or pin 30, arrangedwithin the blank, acts like a mandrel, and the lower portion of theblank is thus extruded downwardly, in the direction of ram movement. Byappropriately sizing the blank at the outset, the extruded part 32 is ofthe proper length and its body portion is of the predetermined OD. andLD.

Thereafter, the extruded part 32 is placed into a second die 33 having asecond die opening 34, which die is mounted upon the press bed or table21. A second punch 35 is mounted upon the ram 28 for downward movementthrough the part.

This second punch is formed with a widened upper end portion 36 of adiameter corresponding to the part O.D., a mid portion 37 correspondingto the part flared [.D., and a tapered part 38 integral with a lowerstraight pin or spindle portion 39, corresponding to the diameter of thebore of the body of the part.

The downward movement of the second punch 35, expands the upper flaredportion of the part to its predetermined OD. and simultaneously expandsthe upper ends of the bore into the predetermined flared portion I.D.FIG. 7 illustrates, in dotted lines, the upper portion of the partfollowing the extrusion step of FIG. and in solid lines indicates thepart following the expansion step of FIG. 6.

As is conventional, the blank and the extruded part 32 and also thepunches and die openings may be suitably covered with conventionallubricants used in forging or cold forming. In addition, depending uponthe type of metal involved, it may be necessary to heat treat the partbetween the extrusion and expansion steps for stress relief, etc., allin the conventional manner.

With the process as described above, the amount of press pressure,meaning size of the press, is considerably reduced, compared to theprior method for forming such parts. For example, in theprior method,press pressure of up to approximately 2,500 tons was required during theseveral steps. Here, press pressure can run up to roughly 800 tons forthe extrusion step and up to 900 tons for the expansion step.Preferably, the part is warmed to a point well below its transitiontemperature for ease in press forming. For example,

7 where the metal may have a transition temperature of roughly 1,700F,it would be desired to warm the metal to somewhere up to the range ofabout l,200F.

The press pressures and warming temperatures given above are allillustrative, and of course, may vary depending upon the specific typeof metal involved. However, it can be seen that the net result of thisprocess is a considerable reduction in pressure and a substantialincrease in accuracy of the finished part, as compared with the priorart method of forming such parts.

Having fully described an operative process, we now claim:

l. A process for cold forming an extruded, tubular metal part having anend portion whose OD. and ID. are flared relative to the body of thepart, in a press having a fixed lower support and a downwardly movablepressure ram, comprising:

positioning a short tubular, vertically axised blank,

whose 0D. is approximately equal to the CD. of the finished part, intothe upper end portion of a vertically axised die opening formed in a diemounted upon the press support, which opening upper end portion is of adiameter to closely receive the blank, with the lower portion of saidopening corresponding to the CD. of the body of the part;

extruding the lower part of the blank downwardly into the said dieopening by means of moving downwardly a press ram mounted punch havingan upper end portion closely fitted into the die opening upper end aboveand pressing downwardly against the upper end of the blank, and a punchlower end elongated cylindrical shape portion extending through theblank and a considerable distance downwardly through the die openinglower portion for thereby extruding the part into a flared upper endportion OD. and a substantially uniform lower end portion CD. of smallerdiameter and a uniform I.D. throughout its length; thereafterpositioning the extruded part in a vertical axis, with its flared endup, in a second vertically axised die opening within a die mounted uponthe press support, which second opening is formed to correspond to thefinished CD. of the part; then expanding the flared upper end portion ofthe part outwardly to form its finished flared portion OD. and LB. bymeans of pressing downwardly through the part central opening a secondpunch mounted upon the press ram, which second punch is formed with anupper end portion of a diameter correspondingto the finished ID. of theflared upper end portion of the part, and an elongated lower end portionof a diameter corresponding to the ID. of the body of the part and of alength to extend a considerable distance through the body of the part,with the two punch portions integrally joined by a tapered centralportion, for thereby expanding the part to finished ID. and OD. flareddimensions. 2. A process as defined in claim 1, and including warmingthe metal to a temperature well below the structural transitiontemperatures prior to each of the press extrusion and expansion steps.

3. A process for forming an elongated tubular metal part having an endportion flared into a larger OD. and 1.0. than the body of the part,comprising:

forming a short, cylindrical, centrally bored metal blank having an OD.corresponding roughly to the CD. of the part flared end;

inserting said blank into a fixed die opening having its entry endportion diameter formed approximately equal to the blank OD. and theremainder of the opening being of a diameter approximately equal to theCD. of the body of the part;

extruding the inner end portion of the blank into the opening by movinga punch into the die opening with a portion of the punch pushing againstthe exposed end of the blank and a second portion of the punch extendingthrough the blank into the die ished OD. and ID. by pressing a secondpunch through the central bore of the part, the central punch being ofstepped diameters to correspond to the part body ID. and the part flaredend portion ID. for expanding the end portion of the part into finisheddimensions between the corresponding punch and die opening surfaces.

1. A process for cold forming an extruded, tubular metal part having anend portion whose O.D. and I.D. are flared relative to the body of thepart, in a press having a fixed lower support and a downwardly movablepressure ram, comprising: positioning a short tubular, vertically axisedblank, whose O.D. is approximately equal to the O.D. of the finishedpart, into the upper end portion of a vertically axised die openingformed in a die mounted upon the press support, which opening upper endportion is of a diameter to closely receive the blank, with the lowerportion of said opening corresponding to the O.D. of the body of thepart; extrudinG the lower part of the blank downwardly into the said dieopening by means of moving downwardly a press ram mounted punch havingan upper end portion closely fitted into the die opening upper end aboveand pressing downwardly against the upper end of the blank, and a punchlower end elongated cylindrical shape portion extending through theblank and a considerable distance downwardly through the die openinglower portion for thereby extruding the part into a flared upper endportion O.D. and a substantially uniform lower end portion O.D. ofsmaller diameter and a uniform I.D. throughout its length; thereafterpositioning the extruded part in a vertical axis, with its flared endup, in a second vertically axised die opening within a die mounted uponthe press support, which second opening is formed to correspond to thefinished O.D. of the part; then expanding the flared upper end portionof the part outwardly to form its finished flared portion O.D. and I.D.by means of pressing downwardly through the part central opening asecond punch mounted upon the press ram, which second punch is formedwith an upper end portion of a diameter corresponding to the finishedI.D. of the flared upper end portion of the part, and an elongated lowerend portion of a diameter corresponding to the I.D. of the body of thepart and of a length to extend a considerable distance through the bodyof the part, with the two punch portions integrally joined by a taperedcentral portion, for thereby expanding the part to finished I.D. andO.D. flared dimensions.
 2. A process as defined in claim 1, andincluding warming the metal to a temperature well below the structuraltransition temperatures prior to each of the press extrusion andexpansion steps.
 3. A process for forming an elongated tubular metalpart having an end portion flared into a larger O.D. and I.D. than thebody of the part, comprising: forming a short, cylindrical, centrallybored metal blank having an O.D. corresponding roughly to the O.D. ofthe part flared end; inserting said blank into a fixed die openinghaving its entry end portion diameter formed approximately equal to theblank O.D. and the remainder of the opening being of a diameterapproximately equal to the O.D. of the body of the part; extruding theinner end portion of the blank into the opening by moving a punch intothe die opening with a portion of the punch pushing against the exposedend of the blank and a second portion of the punch extending through theblank into the die opening smaller diameter portion, for therebyextruding the blank into approximate body O.D. and I.D. and approximateflared portion O.D.; thereafter inserting the extruded part into asecond fixed die opening of a size corresponding to the finished partsize, with the flared diameter of the part at the open end of the dieopening; and expanding the part flared end portion into finished O.D.and I.D. by pressing a second punch through the central bore of thepart, the central punch being of stepped diameters to correspond to thepart body I.D. and the part flared end portion I.D. for expanding theend portion of the part into finished dimensions between thecorresponding punch and die opening surfaces.